1. Field of the Invention
The present invention relates to a filter core and a manufacturing method thereof, and in particular to a filter core for filtering suspended particles from fluid.
2. Description of the Prior Arts
A conventional filter cartridge comprises a filter frame and a filter core. The filter core is mounted in the filter frame, and comprises a wavy filtering sheet and a flat filtering sheet. The filtering sheets are rolled into the shape of a cylinder and are alternately stacked to form multiple axial channels, which have the same shape and size. Each of half of the channels is coated with an end sealing adhesive layer at an axial end adjacent to the inlet of the housing to seal said channel. Each one of the other half of the channels is coated with an end sealing adhesive layer at an axial end adjacent to the outlet of the housing to seal said channel. Therefore, the fluid to be filtered enters half of the channels, flows along said half of the channels, hits the end sealing adhesive layer adjacent to the outlet, and thus passes through the wavy filtering sheet and the flat filtering sheet to the other half of the channels, such that the fluid can leave the filter core. The fluid is filtered to make dust in the fluid attached to the wavy and the flat filtering sheets when the fluid passes through the wavy and the flat filtering sheets.
When the filter core is manufactured, first, the two filtering sheets are adhered with each other via one of the end sealing adhesive layers. Then, a pressing roller presses a side of the adhered filtering sheets along an outer side of said end sealing adhesive layer. Afterward, the other end sealing adhesive layer is coated on the pressed filtering sheets, and finally the two filtering sheets are rolled into the filter core. The pressed side of the filtering sheets becomes an outlet side of the filter core, such that a sectional area of an outlet opening is larger than a sectional area of an inlet opening in each channel. Therefore, the impedance and an aerodynamic force needed when an engine is motivated are both reduced, which saves the energy. However, the above-mentioned pressing step has the following shortcomings:
First, the site of the pressing is disposed in an outer side of the end sealing adhesive layer. Thus, the pressing makes the end sealing adhesive layer, which is not solidified yet, easily spread toward an inner side of the end sealing adhesive layer (toward the center of the filtering layers). Consequently, the end sealing adhesive layer spreads to the two sides in different quantities, with one of the two sides of the end sealing adhesive layer having insufficient adhesion. Therefore, after pressing, the above filtering sheet may rebound upward, which enlarges the space between the two filtering sheets. Thus, the glue to form the end sealing adhesive layer is not sufficient, and bubbles may be incurred in the end sealing adhesive layer, which makes the end sealing adhesive layer incapable of sealing the channels effectively.
To solve the above-mentioned problem, the manufacturer may use larger quantity of glue to form the end sealing adhesive layer. However, the larger quantity of glue requires more time to be solidified. The glue does not have the adhering effect until solidified. Thus, larger quantity of the glue requires more time to ensure the two filtering sheets are adhered securely.
Second, when pressing the two filtering sheets, the glue that spreads toward the outer side of the end sealing adhesive layer may leak in excess, particularly to the situation when larger quantity of the glue is used. Thus, the end sealing adhesive layer cannot be coated at a position too close to an edge of the filtering sheet. So a part that is not coated of the filtering sheet is reserved, and the reserved part is cut off in the final step. However, the cutting device and the cutting step take time and effort. In addition, if the coating position is too far from the edge of the filtering sheet, the filtering area is reduced, too.
To overcome the shortcomings, the present invention provides a filter core and manufacturing method thereof to mitigate or obviate the aforementioned problems.